510 mammalian remains in derwent river-gravels. [aug. 1896, 



Discussion. 



The President congratulated the Authors on their remarkable 

 find, and on the splendid specimens exhibited by them. The mode 

 of preservation of the fossil remains reminded one of that of the 

 Endsleigh Street mammoth-remains, and in both cases it was no 

 doubt attributable to the covering of the deposits by a clayey layer. 

 Indeed, as a whole, the conditions much resembled those of the 

 Thames Yalley : there, as in the Derwent Valley, were plateau- 

 gravels and low-level gravels. He enquired whether certain de- 

 posits marked on the section exhibited were not originally one sheet 

 of gravel, rather than several distinct terraces. If Mr, Deeley's 

 view of the Interglacial age of the fossiliferous deposits was correct, 

 we had here another point of resemblance with the Thames Valley 

 deposits. 



Mr. Reid congratulated the Authors, and hoped that they would 

 continue to search the deposit for further evidence of the climatic 

 conditions. He doubted whether surface-contortion in gravel was 

 sufficient evidence of glacial action or of an Arctic climate. 



Mr. E. T. Newton also spoke. 



Mr. Deelet, who replied on behalf of Mr. Arnold-Bemrose and 

 himself, thanked the .Fellows who took part in the discussion for the 

 considerate way in which they had criticized some of the points 

 raised in the paper. At so late an hour he thought that it was 

 impossible to discuss the question of the origin of the 'trail'; he 

 therefore contented himself with remarking that, just as Mr. Reid 

 had held with regard to the Bagshot Sands, it was necessary to 

 examine the ground mile by mile, and map and compare the deposits 

 with each other, so in the case of the ' underplight ' it was necessary 

 to take into account its local peculiarities in order to form a correct 

 conclusion as to the agent which produced it. In reply to the 

 President's question concerning the relationship between the various 

 high-level terraces of the Trent and Derwent, a section through the 

 gravels of Weston-on-Trent was instanced. Here there are three 

 high-level terraces, the escarpments of the two upper ones seeming 

 to have been obliterated by the agent which produced the flexures 

 of the ' underplight.' In the operation of excavating the valley the 

 erosive action of the stream exerted itself both horizontally and 

 vertically, and the river always left behind it a sheet of gravel. 

 Each terrace is consequently a fragment, which has escaped denu- 

 dation, of the gravel-plain formed when the river ran at that 

 particular level, the highest being the oldest, and the lowest the 

 most modern : the connecting gravel-areas which separated the 

 terraces having been denuded as the rivers wandered from side to 

 side of their valleys. 



